Method of extension blow-molding container having upper and lower sections of different thickness

ABSTRACT

A container having upper and lower portions, the lower portion having self-supporting side walls and a bottom wall. The upper portion is flexible and non-self-supporting. Preferably, the upper and lower portions are formed of plastic material with the upper portion forming a unitary continuation of the lower portion. The entire container may be formed using blow molding techniques or other conventional means such as co-extrusion.

This application is a continuation of U.S. application Ser. No. 123,325filed on Nov. 20, 1987, now U.S. Pat. No. 4,836,970, which applicationin turn is a continuation of Ser. No. 8,658 filed on Jan. 30, 1987 (nowabandoned).

BACKGROUND OF THE PRESENT INVENTION

The present invention relates to a container and methods for forming thecontainer. Particularly, the present invention relates to a disposableand/or reusable container formed of plastic material and methods offorming the container.

Different types, styles, and constructions of containers have long beenknown and used in the past. Likewise, many different materials have beenused in the manufacture of containers. For example, the common paperbag, comprised of four side walls, and a bottom wall formed fromoverlapping and glued flaps of paper, is a well-known constructioneminently suitable for its purpose. Cardboard containers, such as boxes,are also quite common and have been provided in various configurationsand constructions for a variety of purposes. Plastic containers, such asbottles for containing liquids or thin film plastic bags for disposingof trash, are likewise well known and variously constructed and used.Containers formed of plastic materials have significant advantages incomparison with prior paper or cardboard containers. For example,plastic containers are strong, resilient, long-lasting, and inert tomost items disposed in the container. They are also suitable forcontaining and confining fluid materials. Additionally, plasticcontainers may be currently produced at extremely low cost and maytherefore constitute throwaway or disposable items after use. Commonplastic containers of the thin film type, however, have a significantdisadvantages in comparison with paper or cardboard containers in thatthe latter are generally self-supporting or freestanding in theirintended shape. On the other hand, containers formed of thin plasticfilm are generally not capable of assuming or maintaining apredetermined shape.

Further, in many environments, paper, cardboard and plastic bags are notsuitable for use alone and must be used in conjunction with othercontainers or support structure. For example, it is common practice toprovide a container formed of a self-supporting plastic material andthen to line the container with a paper or plastic bag. Paper bagliners, of course, lack strength, resilience and the capacity to containand confine liquid materials. Plastic bag liners, on the other hand, areeasily punctured by the contents of the container. In certainapplications, for example trash disposal, it is also necessary to liftthe paper or plastic liner from the supporting container and replace itwith a fresh paper or plastic bag liner. Paper or plastic bag linersfrequently break or tear when lifted from a supporting container.Tearing is often caused by depositing material into a plastic liner andfrequently, in the case of paper liners, by a weakening of the bag inthe areas where fluid has been absorbed. Additionally, when such paperor plastic liners fail, the supporting container usually must becleaned.

Additionally, thin film plastic bags or containers are well known andcommonly used by themselves without any supporting structure. However,because these bags are not self-supporting or freestanding, greatdifficulty attends their filling in the absence of an ancillary supportstructure. For example, thin film plastic bags are commonly used fordisposing of leaves. However. filling these bags with leaves or evenmaintaining the bag open for filling purposes is difficult because thebags will collapse absent a supporting structure. Thin film plastic bagsthus do not have shape-retaining characteristics.

SUMMARY OF THE PRESENT INVENTION

In accordance with the present invention, there is provided a containercomprised of an enclosure having upper and lower portions, the lowerportion including self-supporting side walls and a bottom wall. Theupper portion of the container is flexible and non-self-supportingwhereby the container may stand in an upright orientation with the sidewalls supporting the upper and lower portions. Preferably, the sidewalls of the lower portion are formed of a plastic material ofpredetermined thickness, while the upper portion is likewise formed of aplastic material of a predetermined thickness less than the thickness ofthe plastic material forming the lower portion. Thus, the lower portionis formed of a plastic material having a wall thickness sufficient suchthat the container is self-standing or self-supporting. The wallthickness of the lower portion can also be modified as desired so as tobe sufficient to avoid puncturing by materials disposed within thecontainer, and to afford sufficient strength and rigidity to maintainthe container in its intended configuration without significantdistortion or flexing.

The upper portion of the container preferably constitutes a flexibleintegral extension of the side walls of the lower portion. That is, theside walls and the upper portion are of unitary one-piece plasticconstruction one with the other with the upper portion constituting athin film of plastic material forming a continuation of the side walls.As alluded to hereinafter, the flexible upper portion terminates in afree end which may be gathered together and secured, for example, by atie, to close the upper end of the container. With the container thusclosed, it may be transported as desired and, if used as a trashcontainer, may be discarded and disposed of together with the trashcontained therein.

A significant advantage of the present invention resides in thepreferred unitary one-piece or integral construction of the container.This enables the container to be produced at low cost and, thus bedisposable or reusable as desired. On the other hand, the container mayalso be constructed in other ways, such as by the attachment via heatsealing (or other well known means) of a separately formed upper portionto the lower portion.

Accordingly, and in accordance with another aspect of this invention,the container may be formed using blow-molding techniques. To accomplishthis, the plastic material is extruded from a die head to form aparison. When extruding the material, the die head preferably firstextrudes a thin film of the plastic material to form a first parisonsection which eventually will form the upper flexible portion of thecontainer. The die head is then adjusted to extrude plastic material toform a second parison section having a greater wall thickness than thefirst parison section and which will ultimately form the lower portionof the container. After such extrusion, opposed mold platens, whichstraddle the parison, move under the extrusion head to close about theparison. As the mold platens close about the parison, a blow pin isinserted into the mold and parison. The parison is then inflated byintroducing air through the blow pin and into the parison to form theplastic material to the desired configuration. Upon subsequent removalfrom the mold and inversion, there is thus formed a unitary one-piececontainer having a flexible upper portion and a lower portion havingself-supporting side walls and a bottom wall.

Where the container hereof is intended in use to displace containershaving disposable liners as discussed above, it will be appreciated thatthe present container does not require a separate liner. The lowerportion affords the necessary structural strength to support thecontainer and to maintain its container shape and integrity. The upperportion permits ready and easy closing of the container, for example, byusing conventional ties. The low cost of the plastic materials formingthe container and the use of blow molding techniques enables thecontainer to be economically disposable. The container may also, ofcourse, be reused if desired. Furthermore, because of the variablethickness of the side walls and bottom wall, the container may holdsharp objects, for example, broken glass or disposable hospitalparaphernalia including syringes, etc., without being punctured, torn orripped as might otherwise happen when using paper or thin film plasticliners in rigid containers.

Additionally, handles may be formed in either the lower self-supportingportion or the upper flexible portion of the container or both. Thus, inthe molding process, indentations may be provided along opposite sidesof the lower portion of the container to provide finger grips. Othertypes of handles may obviously be accommodated in the molding processand applied to the lower portion. The upper flexible portion may beprovided in the mold with additional handles or may be cut to formhandle openings along opposite sides and adjacent the upper free endthereof. Thus, the container may be lifted using the handles formed inthe flexible portion or by handles formed in the structural lowerportion as desired.

Another important aspect of the present invention resides in thecapability of stacking containers constructed in accordance with thisinvention. To accomplish this, the side walls of the lower portion maybe tapered outwardly and upwardly such that the containers may be nestedone within the other for transportation and storage prior to use. Toaccommodate this, the flexible upper portion of each container may bedisposed within the lower portion. Thus, when the containers are nested,the upper portion may be disposed between its associated lower portionand the next adjacent container when the latter is nested into theformer. Alternatively, if the upper flexible portion is likewisetapered, the flexible upper portion may project away from the lowerportion. The containers may thus be nested with the flexible portionextending from each container. A further alternative includes collapsingthe flexible upper portion externally about the lower portion. Thus, theflexible portion, when the containers are nested, may be either receivedwithin the adjacent container or extended about the adjacent container.

A further optional feature of the present invention includes a cover forthe container. In this form, the cover may be formed by conventionalblow-molding or other known plastic molding techniques. Fastening meansare preferably provided adjacent the margin of the cover for releasablysecuring it to the upper margin of the lower portion of the container.Such releasable securing means may take the form of screw threads,interlocking lugs, bayonet-type joints, or key and keyhole slot typejoints. A cover is useful in those situations where the material in thecontainer is required to be or should be covered. In practice, the covermay be formed of substantially rigid plastic material. It may bedisposable along with the container, may be reusable with otherdisposable containers or used for so long as the container is used andreused.

Accordingly, it is a primary object of the present invention to providea novel and improved container and a method of forming the containerwhich minimizes or eliminates the foregoing and other drawbacks anddisadvantages of prior containers. The container of the presentinvention is simple and inexpensive to construct, readily disposed in astacked or nested condition for transportation, storage, and/or use anddisposable or reusable as desired. It has puncture-proof and fluidretention characteristics, and importantly, may be formed simply, easilyand inexpensively of unitary one-piece plastic material.

It is specifically contemplated that the present invention shall have avery wide variety of potential usages. For example, it can be used forholding trash, storing materials, shipping chemical, packaging food(milk, cheese, ice cream and the like), etc. The foregoing examples areonly some of the potential uses of the invention and are not meant to bea complete listing of all possible uses.

These and further objects and advantages of the present invention willbecome more apparent upon reference to the following specification,appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a perspective view of a container constructed in accordancewith the present invention and illustrating the upper portion of thecontainer in an open condition;

FIG. 2 is a fragmentary view similar to FIG. 1 illustrating the upperportion of the container in a closed condition with one form of aclosing device therefor;

FIG. 3 is a view similar to FIG. 2 illustrating another form of closingdevice for the upper portion of the container;

FIG. 3a is an enlarged fragmentary perspective view of a portion of theclosing device for the container illustrated in FIG. 3;

FIG. 4 is an enlarged fragmentary cross-sectional view taken generallyabout on line 4--4 in FIG. 1;

FIG. 5 is a horizontal cross-sectional view of a cylindrical containerconstructed in accordance with the present invention and taken throughthe lower portion thereof;

FIG. 6 is a view similar to FIG. 5 and illustrating a containergenerally rectangular in cross-section constructed in accordance withthe present invention;

FIG. 7 is a side elevational view with portions in cross-sectionillustrating containers hereof in a stacked or nested condition;

FIG. 8 is a view similar to FIG. 7 illustrating another configuration ofstacked containers;

FIG. 9 is a perspective view of the container hereof illustratinghandles or grips on both the lower and upper portions;

FIG. 10 is a cross-sectional view of a container constructed inaccordance with the present invention and illustrating its use with adetachable cover; and

FIG. 11 is a schematic view illustrating a method of forming a containerconstructed according to the present invention.

DETAILED DESCRIPTION OF THE DRAWING FIGURES

Reference will now be made in detail to the preferred embodiment of thepresent invention, several examples of which are illustrated in theaccompanying drawings.

Referring now to the drawings, particularly to FIG. 1, there isillustrated a container, generally designated 10, constructed inaccordance with the present invention. The container 10 includes lowerand upper portions 12 and 14, respectively, preferably formed of aunitary one-piece plastic construction. Container 10 also includes abottom wall 16 (FIG. 6) which is also preferably formed unitarily withthe lower and upper portions 12 and 14, respectively, of container 10.Lower and upper portions 12 and 14, respectively, are also generallytubular in cross-section and the side walls thereof may have any desiredcross-sectional shape, i.e., circular, square, rectangular, etc., at anyelevation along the height of the container.

It is a particular feature of the present invention that the lower andupper portions 12 and 14, respectively, of container 10 are formedintegrally of a plastic material having different thicknesses. In apreferred form of the present invention and as best illustrated in FIG.4, the lower portion 12 has side walls formed of a plastic materialhaving a wall thickness t1. Thickness t1 is sufficient such that theside walls are self-supporting. That is to say, the side walls ofcontainer 10 are sufficiently rigid or structural so that the containerin its upright position is self-standing or self-supportable. In thisconnection, where the side walls form the self supporting means, thebase or bottom wall 16 can be of any thickness desired by the user,including being of the same thickness a upper portion 14.

Not only does this afford stability to the upstanding container 10, butalso provides a container which is relatively puncture-proof, hassufficient self or structural rigidity to retain its shape as acontainer, and is leakproof. Thus, the advantages and benefits whichaccrue to conventional containers formed of plastic material and whichcontainers retain their shape, definition and integrity as a plasticcontainer of predetermined configuration will likewise accrue tocontainer 10 hereof.

The upper portion 14 of container 10 is formed integrally or unitarilywith lower portion 12 and of the same plastic material, as will beapparent from the ensuing description. The plastic material forming theupper portion 14 preferably, and in accordance with the presentinvention, has a wall thickness t2 which is normally substantially lessthan the thickness t1 of the side walls of lower portion 12. However, itshould be noted that the particular thickness of the upper and lowerportions is also dependent upon the materials selected. Since anyplastic, or equivalent, material may be utilized it can be envisagedthat different materials will be used to form the upper and lowerportions. As a result, the thickness of the upper flexible portion may,with the appropriate selection of materials, be about the same thicknessas the self-supporting side walls of the lower portion.

Particularly, the wall thickness t1 of upper portion 14 is such thatupper portion 14 comprises essentially a thin film of plastic materialwhich is highly flexible and non-self-supporting. By non-self-supportingis meant that, in the absence of other support structures and anystructural rigidity imparted to the upper portion by its tubular shape,the film of material would collapse of its own weight onto itself. Thus,because the upper portion constitutes a tubular thin film extension ofthe self-supporting tubular lower portion, it will, to a limited extentand by virtue of its tubular construction and that of the lower portion,stand up of its own accord but would otherwise be collapsible under itsown weight. Thus, it will be appreciated that in accordance with thepresent invention there is provided a container wherein the side wallsof the lower portion 12 are formed of a plastic material of apredetermined thickness wherein the side walls are self-supporting whilethe upper portion is formed of a flexible plastic material of athickness less than the thickness of the plastic material forming thelower portion.

Preferably, the container hereof is formed integrally of high-densitypolyethylene. Other types of plastic or comparable materials, however,may be used, such as low-density polyethylene, polypropylene or otherplastic olefins.

In forming the unitary container hereof, the lower portion may be formedof plastic material having a wall thickness t1 of about 5-250 mils,whereas the wall thickness t1 of the upper portion 14 may be about 1-40mils. However, it will be recognized that thicknesses outside of theseranges can be used for certain applications, provided only, however,that lower portion 12 have side walls which are self-supporting orself-standing and upper portion 14 have side walls formed of a flexiblematerial which can be folded, gathered or collapsed and which, ofitself, is non-self-supporting.

As indicated previously, container 10 may be provided in variousconvenient shapes. For example, in the container illustrated in FIG. 1,the lower portion 12 is generally rectilinear having opposed parallelside walls. In FIG. 5, the lower portion 12a of container 10a isgenerally frustoconical in shape wherein lower portion 12a tapersupwardly and outwardly from bottom wall 16a. In the form of containerhereof illustrated in FIG. 6, the lower portion 12b of container 10b hasside walls which taper outwardly and upwardly from bottom wall 16b.Other configurations of the lower portion of the container hereof willbe readily apparent.

The upper portion 14 of the container is preferably similarly shaped incross-section as lower portion 12. Preferably, it comprises a tubularextension of the same cross-sectional configuration as lower portion 12.Where the lower portion tapers upwardly and outwardly, the upper portionmay likewise continue the upward and outward taper of the lower portion,e.g., as illustrated in FIGS. 8 and However, it is not necessary thatthe upper portion conform to the taper of the lower portion.

Turning back to FIGS. 1 and 2, it will be appreciated that container 10may be disposed in an upright self-supporting condition wherein theupper margin of lower portion 12 forms an opening into the container.The upper portion 14 in use may be folded back about the side walls oflower portion 12 externally of the container. The container may then befilled as desired. When full, upper portion 14 is then disposed abovelower portion 12 as illustrated in FIG. 1 and gathered, folded orcollapsed into the condition illustrated in FIG. 2, to form a neck 18 ofreduced diameter. Because the material forming upper portion 14 isflexible, e.g., formed of thin plastic film, upper portion 14 may bereadily gathered, collapsed or folded to form neck 18. A conventionalpaper-covered wire tie 20 may then be wrapped about upper portion 14 atneck 18 to close the container. Container 10 may be discarded in itsentirety, whereby container 10 constitutes a disposable container.

Alternatively, the container, with its upper portion 14 open, may beemptied of its contents and reused. Because the materials forming thecontainer are relatively inexpensive and the different thicknesses ofthe materials of the container are readily and easily formed inavailable molding machinery as set forth below, it will be appreciatedthat there is provided a relatively inexpensive container which may beeither disposable or reusable.

In either use, the present container avoids the problems associated withprior rigid containers, such as trash containers wherein disposableliners are provided as separate and separable elements forming part ofthe trash container, yet provides many of the advantages of aconventional non-self-supporting thin film plastic bag in the provisionof a flexible upper portion for the container hereof which may begathered and tied off to close the container. The present container isthus a hybrid of substantially rigid and thin film containers havingcertain of the advantages of both, the disadvantages of neither, andaffording certain additional benefits as may be realized from thisdescription. In this regard, it is believed significant that, althoughsuch prior art containers have been in existence for many years priorhereto, applicant is unaware of any use, sale or manufacture of thepresent invention. Such evidence speaks eloquently of the unobviousnature of this invention.

Referring now to FIGS. 3 and 3a, the upper portion 14 of container 10may be provided with many other forms of closure, for example, adrawstring. In this form, a passage 22 is formed about the upper marginof upper portion 14 by folding over that margin as illustrated at 24 andheat sealing it to upper portion 14. A cutout 26 may be formed in oneside of the margin, enabling a drawstring 28 to be threaded throughpassage 22. The drawstring may comprise a flexible plastic band or acord or other suitable material. Suffice to say, when the container isfilled, the drawstring 28 may be pulled to gather the upper portion 14and tied to effect closure of the container.

In one important aspect of the present invention, the containers hereofare provided in configurations wherein they can be stacked or nestedwith one another to minimize the space required for transportation andstorage. Additionally, the containers may be used in their stackedcondition by using the uppermost stacked container, removing it whenfilled from the stack and then using the next stacked container. To thisend and as best illustrated in FIGS. 6 through 8, the containers arepreferably formed in a tapered configuration. Thus, each of the sidewalls of the lower portion 12b tapers upwardly and outwardly relative tothe other side walls and from the bottom wall whereby the containers canbe nested one within the other, as illustrated in FIG. 7. In one form ofnested or stacked containers, the upper portion 14b may be folded withinthe container prior to stacking. An upper nesting container may then beinserted bottom first into a lower container such that the upper portion14b of the lower container is disposed between the side walls formingits lower portion 12b and the side walls of the lower portion 12b of theupper container.

Alternatively, and as best illustrated in FIG. 8, the upper portions 14bof the stacked or nested containers may extend outwardly in a directionaway from lower portion 12b. In this form, each nested container isreceived within the underlying container and the upper portion of thereceiving container overlies the outer upper margins of the nestedcontainer. Alternatively, the containers may be stacked with the thinportions folded over the outside of the side walls of the container.

In a further form of the invention illustrated in FIG. 9, integrallyformed handles are provided container 10c. In one form, such handles maycomprise indentations 32 integrally formed in the side walls of thelower portion 12c to provide lifting grips whereby the container 10c maybe lifted. Alternatively, other types of handles may be provided thelower rigid self-supporting portion 12c, such as pivoted wire or plastichandles. Suffice to say, handle grips 32 provide a ready and convenientway to grip or grasp the container when it is necessary to lift thecontainer.

In another alternative embodiment, handles may be provided upper portion14c. In one form, slots or cutouts 34 may be formed in either or both ofthe opposite sides of upper portion 14c. Thus, an individual wishing tolift the bag, may grab container 10c by inserting his hands through theslots 34.

Alternatively, the upper portion 14c may be gathered such that handles34 register one with the other whereby an individual's hand may beinserted through both slots 34. It will also be appreciated that othertypes of handles may be provided upper portion 14c. For example, loops,not shown, may be integrally formed to project from the upper margin ofupper portion 14c at oppositely located positions, similarly as cutouts34 are located, whereby the loops can be grasped to lift container 10c.The handles provided upper portion 14c and lower portion 12c may beprovided alternatively or conjunctively.

Referring now to FIG. 10, a cover or lid 40 may be provided container10d. Cover where it is desirable to releasably seal the container 10d orprovide a more rigid cover for the container. In this form, cover 40 hasa top 42 and depending side walls 44 which substantially conform to thecross-sectional shape of the upper margin of lower portion 10d. It canbe of any shape and/or have any type of sealing means so long as itserves to act as a cover.

Thus, in the illustrated closed position of cover 40, side walls 44telescope over the upper margin of lower portion 12d. Along one sidewall 44, there is provided a key for engaging in a key slot formed alonga wall portion of lower portion 10d, enabling the cover to be hingedlymounted to container 10d. At the opposite side of the cover from thehinged mounting, a latch 46 is provided whereby the cover may bereleasably secured in the illustrated closed position and pivoted backabout the hinge to an open position. Upper portion 14d of container 10d,because of its flexible nature, may be simply collapsed onto itself whenthe cover 40 is moved to close the container.

Alternatively, upper portion 14d may be closed, as in FIGS. 2 or 3,before the cover is pivoted down into its closed position, thuseffecting a double seal. Preferably, the cover 40 is releasably securedto container 10d so that it may be wholly . detached from the container.This enables cover 40 to be reusable with other containers.Alternatively, the cover, being formed of similar inexpensive materialsas container 10d, may be disposable with container 10d, as desired.

Referring now to FIG. 11, there is provided a schematic illustration ofapparatus useful for the manufacture of the containers described above.According to the present invention, the container hereof may bemanufactured using blow molding apparatus. In this apparatus, plasticmaterial is disposed in a hopper 50 which transfers the material to anextruder 52. Thus, the raw plastic material is fed from hopper 50 intoextruder 52, where it is plasticized and transported to an accumulator54, having a lower die head 56. Die head 56 includes a variable widthslit formed between two mold parts, the slit being in the general shapeof a circle. The wall thickness of the resulting container may beregulated by a conventional thickness control indicated 58.

Below die head 56 are located a pair of mold platens 60, movable towardand away from one another along suitable guides 62. Preferably, ahydraulic mechanism, not shown, is used to move the mold platens 60toward and away from one another. The mold platens have mold surfaces64, which conform to the shape of the final product. In this case, themold surfaces 64 are semi-cylindrical surfaces tapered outwardly anddownwardly from top to bottom, for reasons discussed hereinafter.

Below the die head and the mold platens 60 is a blow pin 66, which isadjustable in height by a suitable hydraulic mechanism 70. The blow pinis used to blow air into the parison P when the mold is closed.

To form the container hereof, mold material flows through hopper 50,extruder 52, into the accumulator 54 for extrusion through the slit inthe die head 56. The mold material, preferably polyethylene, is extrudedfrom the slit in the form of a cylindrical parison P, which is open atits lower end. When a suitable length of parison p has been extruded,the blow pin 66 is adjusted to enter the open end of the parison and themold platens 60 are moved toward one another to close about the parison.Air is then ejected through the blow pin into parison P to inflate itfor conformance to the mold walls of mold platens 60. It will beappreciated that the closing of the mold pinches off the upper end ofparison P and the inflation of the parison forms closed upper and lowerends within the mold.

In accordance with the present invention, the plastic material isextruded from the die head 56 to form a first parison portion P1 havinga predetermined thickness. The thickness control 58 is operated suchthat a second parison portion P2 is formed having a thicknesssubstantially greater than the thickness of the plastic material formingparison portion P1. The parison portion P1 corresponds to the plasticmaterial which will ultimately form the upper portion 14 of thecontainer while the parison portion P2 comprises the plastic materialwhich will ultimately form the lower portion 12 of the container 10.Consequently, it will be appreciated that the molding of the containershown here is accomplished in an inverted manner, upper portion 14 beingextruded from the die head 56 prior to extrusion of the lower portion12. The walls 64 of the mold platens, as illustrated, are tapered in adownwardly and outwardly direction such that a tapered container may beprovided. Also, the lower end of the product is cut, preferably byexplosion cutting, such that the final product will be open at that end.After cooling, the mold platens are separated and the container isremoved from the blow molding apparatus.

In addition, the present invention also contemplates that the containerbe made by conventional co-extrusion processes whereby any number oflayers of material may be utilized to form the upper and lower portions.Thus, for example, one or more different materials can be utilized tomake the upper and lower portions. This method of production would beuseful, for example, in making food containers. In such an application,the outer layer(s) of the lower portion could be made from plastic togive structural strength while the inner layer(s) could be made from FDAapproved food grade plastic or other non-plastic materials. Of course,in order to make multiple layers, it will be necessary to utilizemultiple extruders and accumulators. Such co-extrusion processes arewell-known in the art.

It will thus be appreciated that in accordance with the presentinvention there has been provided a novel and improved container andmethod of making the container which is relatively inexpensive toconstruct, formed of a one-piece plastic construction, and is eitherdisposable or reusable as desired. It will also be appreciated thatthere are a multiplicity of uses for the container hereof in either itsdisposable or reusable form, including use as a trash container.

While the invention has herein been shown and described in what ispresently conceived to be the most practical and preferred embodimentthereof, it will be apparent to those of ordinary skill in the art thatmany modifications may be made thereof within the scope of theinvention, which scope is to be accorded the broadest interpretation ofthe appended claims so as to encompass all equivalent containers andmethods for manufacturing containers.

I claim:
 1. A method of making a plastic container comprising an enclosure having a generally tubular side wall and an opening formed in said side wall, said method comprising the steps of:forming a generally tubular parison with corresponds to said generally tubular side wall by continually sequentially extruding a tubular parison having one and another portions of predetermined different wall thicknesses from a plastics material such that said one and another portions are integral tubular extensions of one another, and such that the predetermined thickness of said one portion is substantially less than the predetermined thickness of the other portion to impart flexible, gatherable and non-self-supporting characteristics to that region of said generally tubular side wall corresponding to said one parison portion and self-supporting characteristics to another region of said generally tubular side wall corresponding to said another parison portion; disposing said generally tubular parison having said one and another portions in a blow mold having mold walls which are sized and configured to a desired shape of said container; urging said one and another portions into conformance with the mold walls to form said tubular side wall having said non-self-supporting region and said self-supporting region; and forming said opening in said sidewall by removing a part of said plastic material forming said side wall to form the container.
 2. A method as in claim 1 which includes forming said one and another portions integrally of high-density polyethylene.
 3. A method as in claim 1 wherein said another parison portion has a first wall thickness which is substantially self-supporting and corresponds to a lower portion of said container, and said one parison portion has a second wall thickness which is substantially less than said first wall thickness which is to be flexible, gatherable and non-self-supporting and corresponds to an upper portion of said container, and wherein the step of extruding said tubular parison includes extruding said one parison portion prior to sequentially extruding said another parison portion.
 4. A method as in claim 3, including extruding said one parison portion in a generally downward direction followed by sequentially extruding said another parison portion in the same generally downward direction following the one extruded portion, whereby said one and another portions are inverted, and disposing said one and another parison portions in said mold in said inverted position.
 5. A method as in claim 1, wherein said generally tubular side wall of said container is generally cylindrical. 